<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <script src="https://lib.baomitu.com/jquery/2.2.4/jquery.js"></script>
</head>

<body>
    <button id="btn">按钮</button>
    <!-- DOM,BOM,AJAX -->
    <script>
        // var btn = document.getElementById("btn");
        // btn.onclick = function () {
        //     this.innerHTML = "openlayer"
        // }
        /* jquery是一个js的库 简化了操作DOM,简化了http请求 */
        /* $找到 */
        $("#btn").click(function () {
            $(this).html("openlayer")
        })

    </script>
</body>

</html>